This invention relates to push-button devices and, more particularly, to a push-button device specifically suited for use in a watchcase.
A conventional push-button device used in a watchcase generally employs a metallic coil spring through which a shaft portion of a button body extends. The coil spring serves to restore the button body to its original position. This coil spring does tend to be contaminated with water and dust and may therefore corrode and become clogged. This causes the push-button to act improperly. Another problem is that contaminants such as dust which attach themselves to a sealing ring may deteriorate the waterproofing action of the sealing ring.
One example of a conventional push-button device is typified by the structure shown in FIG. 1. As illustrated, a pipe 12 having a stepped portion 12a is secured to a watchcase 10, the shaft portion 14a of a button body 14 is inserted into the pipe 12, and a waterproofing sealing ring or O-ring 16 is disposed between the shaft portion 14a of the button body and the inner wall of the pipe 12. A snap ring 18 is fastened to the end 14b of the button body 14 to prevent the button body from falling out of the case 10. A metallic coil spring 20 is disposed in the clearance formed between the stepped portion 12a of the pipe 2 and the head portion 14c of the button body 14. The coil spring serves to restore the button body 14 to its original position.
While the O-ring 16 succeeds in protecting the interior of the case 10 from the invasion of water, the coil spring 20 does tend to be contaminated with water and dust and may therefore corrode and become clogged. A frequent result is improper push-button action that may not allow normal operation of the push-button. Another problem is that contaminants such as dust which attach themselves to the O-ring 16 may deteriorate the waterproofing action of the O-ring.